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%I #22 Sep 08 2022 08:45:42
%S 1960,9960,17960,25960,33960,41960,49960,57960,65960,73960,81960,
%T 89960,97960,105960,113960,121960,129960,137960,145960,153960,161960,
%U 169960,177960,185960,193960,201960,209960,217960,225960,233960,241960,249960
%N 8000n - 6040.
%C The identity (80000*n^2-120800*n+45601)^2-(100*n^2-151*n +57)*(8000*n-6040)^2=1 can be written as A157628(n)^2-A157626(n)*a(n)^2=1.
%H Vincenzo Librandi, <a href="/A157627/b157627.txt">Table of n, a(n) for n = 1..10000</a>
%H Vincenzo Librandi, <a href="http://mathforum.org/kb/message.jspa?messageID=5773864&tstart=0">X^2-AY^2=1</a>
%H <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1).
%F a(n) = 2*a(n-1) - a(n-2).
%F G.f.: x*(1960+6040*x)/(x-1)^2.
%t LinearRecurrence[{2,-1},{1960,9960},40]
%o (Magma) I:=[1960, 9960]; [n le 2 select I[n] else 2*Self(n-1)-Self(n-2): n in [1..40]];
%o (PARI) a(n)=8000*n-6040 \\ _Charles R Greathouse IV_, Dec 27 2011
%Y Cf. A157626, A157628.
%K nonn,easy
%O 1,1
%A _Vincenzo Librandi_, Mar 03 2009
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